from utils import AlphabetUtils as au


def encrypt_text(cleartext: str, keyword: str) -> str:
	"""
	Encrypts the given text with the given keyword
	:param cleartext: The text to encrypt
	:param keyword: The keyword to use
	:return: The encrypted text
	"""

	# If the ciphertext is longer than the keyword, we need to multiply the keyword
	while len(cleartext) > len(keyword):
		keyword += keyword

	resulting = ''

	for char_index in range(len(cleartext)):
		char = cleartext[char_index]
		key = keyword[char_index]
		cipherchar = _get_corresponding_cipher(char, key)
		resulting += cipherchar

	return resulting


def decrypt_text(ciphertext: str, keyword: str) -> str:
	"""
	Decrypts the given ciphertext with the given keyword
	:param ciphertext: The text to decrypt
	:param keyword: The keyword to use
	:return: The decrypted text
	"""

	# If the ciphertext is longer than the keyword, we need to multiply the keyword
	while len(ciphertext) > len(keyword):
		keyword += keyword

	resulting = ''

	for char_index in range(len(ciphertext)):
		char = ciphertext[char_index]
		key = keyword[char_index]
		clearchar = _get_corresponding_char(char, key)
		resulting += clearchar

	return resulting


def _get_corresponding_cipher(char: str, key: str) -> str:
	"""
	Calculates the corresponding cipher char for the given clearchar/keychar combination using the vigenere square
	:param char: The cleartext char
	:param key: The keyword char
	:return: The cipher char
	"""
	char_index = au.get_index_of_letter(char)
	key_index = au.get_index_of_letter(key)

	# Based on the layout of the vigenere square, this should in theory work
	cipher_index = (char_index + key_index) % 26

	return au.get_letter_at_index(cipher_index)


def _get_corresponding_char(cipher: str, key: str) -> str:
	"""
	Calculates the corresponding cleartext char for the given cipherchar/keychar combination using the vigenere square
	:param cipher: The cipher char
	:param key: The keyword char
	:return: The cleartext char
	"""
	cipher_index = au.get_index_of_letter(cipher)
	key_index = au.get_index_of_letter(key)

	# Based on the layout of the vigenere square, this should in theory work
	char_index = (cipher_index - key_index) % 26

	return au.get_letter_at_index(char_index)


if __name__ == '__main__':
	print(encrypt_text('BonkRocks', 'SuperSecretKeyword'))
	print(decrypt_text('ticoiggmj', 'SuperSecretKeyword'))